You can imagine that adds up to a lot of combinations. But I don't intend to complain here about the number of combinations in testing Actually, on none of these VMs, does this issue reproduce. I have only seen it very occasionally in my own usage, and very rarely in field reports such as your own.

Now the question is, therefore, is there anything you can say, that is particular to your PC/tablet, that may be causing this issue? For example, any particular apps you may have installed, and/or use specifically? If we could reproduce this issue in a VM predictably, that will make our process of fixing the issue much, much, much easier. Which is why I ask - thanks so much Grigoris!

Since the issue is located in the store cache I believe it has nothing to do with the desktop apps right?I have only 15 metro apps installed.I will do some testing by uninstalling them resetting store cache and see if the issue comes up.

Correct. If you could narrow the issue down to one Metro app, that would be great. Then I can experiment with that Metro app until the issue reproduces in a VM, and from there, it would be smooth sailing!

I have tried reproducing the issue by restoring the image I made with the store folder excluded and making a backup but the issue didn't reproduce.So I don't know what to make of this.The apps where the same.So for some reason that specific store cache had issues(maybe caused by the updates installed??)I don't really know.And since I am not at home I had to delete that image(not enough flash memory to keep 2 wim) so I can't pinpoint what caused the issue.

That is correct, your findings are just like my own. The issue is unfortunately intermittent and appears to go away on its own, lending some credence to the theory that it may be an intermittent Windows bug. I am glad you are able to enjoy your full disk compression savings now

Grigoris, after lengthy deliberations on this issue, we are inclined to think that the issue occurs due to an intermittent WoF (Windows Overlay Filter driver) bug (at Microsoft's end). However, we would like to be certain; so the next time you run into this issue, if you could please reach out to us again, we'd like to run a couple of very simple diagnostic commands on your system:

"In other words, does 'wimlib-imagex capture' on just the containing directory consistently fail? If no then it is an intermittent WOF bug. If yes then it could be the case that the reparse point was corrupted somehow, and I'd be interested to see its data (which you can save in a WIM file using 'wimlib-imagex capture' when WOF is not running, e.g. running on a Windows PE based on Windows 7)."

Since this might be a complicated process, and since it must be done before you exclude the folder from compression so as to be able to avoid preventing the issue, I understand if you are unable to assist. However I thought I'd let you know we'd very much appreciate your help if you are able to oblige, and we'd do our best to help you run the necessary tests on your system as easily and quickly as possible.

The first test (running wimlib-imagex capture) is trivial enough and could be done by yourself directly, or by us through a remote TeamViewer connection. Unfortunately the second test we could not directly do remotely, since it would require us to be in front of the PC, rebooting it from a USB removable device with a Windows 7 PE on it; however we will still try to make things as easy as possible for you by preparing the Windows 7 PE image and uploading it for you beforehand, etc.